Dental composite cartridges and ejector-type applicators have been developed to provide an easy method of handling uncured dental composite. Small cartridges which can hold single dosages or only a few dosages of composite have also been developed for obvious sanitation and economic reasons.
One such cartridge is disclosed in U.S. Pat. No. 4,391,590 which relates to a cartridge having one end of a cylindrical hollow body closed by a hemispherical wall. The hemispherical wall has substantially the same uniform thickness as the body. The piston within the body has a complementary inner end which is also hemispherical in shape. The cartridge includes a color-coded cap on its nozzle end to indicate desired properties of the contents of the cartridge.
U.S. Pat. No. 4,963,093 relates to a cartridge having a blunt internal end wall, an internal conically shaped wall surface tapering toward the closed end of the cartridge, and a complementary conical piston. An internal frusto-conical chamber tapering toward the closed end of the cartridge and in open communication with a reservoir portion is also provided.
U.S. Pat. No. 5,129,825 relates to a cartridge or capsule comprising a body portion having a series of circumferentially spaced longitudinally extending ribs. The ribs function to resist any internal build-up of pressure that may be developed during the extrusion of the material from the capsule.
Various problems exist in the above-mentioned cartridges. Most require a complicated and relatively expensive body and piston, and some pistons comprise more than one part, for example, a piston proper and a sealing ring. Most pistons have complicated pressure end surfaces which require the piston to be molded. A need therefore exists for a simple yet effective dental composite cartridge which is relatively inexpensive and easy to manufacture.